This invention relates to multi-purpose probe-based apparatus, and to methods for providing images of surface topography, and detection and quantitative mapping of local mechanical and electromagnetic properties in non-resonant oscillatory mode. These methods may include filtering of incoming probe signals. These incoming probe signals provide time deflection curves, parts of which are used for the control of scanning and collection of data that reflects sample adhesion, stiffness, elastic modulus and viscoelastic response, electric and magnetic interactions. These methods permit adaptive choice of an AFM's deflection set-point, which allows imaging at the contact repulsive force for precise surface profilometry, as non-resonant oscillation brings tip and sample into intermittent contact. These methods permit choosing a desired deformation model that allows an extraction of quantitative mechanical properties including viscoelastic response from deflection curves. These methods also permit local quantitative measurements of tip-sample current and detection of surface potential, capacitance gradients and piezoresponse in non-resonant oscillatory mode. The stable thermal environment reduces apparatus thermal drift and improves apparatus performance.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of on-line analysis of probe deflection signals collected in non-resonant oscillatory mode of AFM or another AFM mode at a sample location, which allows determining the deformation type of said sample, and applying to the collected signals a desired theoretical model for a defined deformation type to extract quantitative values of sample mechanical properties at said location, and repeating the collection steps at a plurality of different locations on said sample during lateral scanning to obtain quantitative maps of mechanical properties and surface topography in height images.
2. The method of claim 1 further comprising filtering of said signals including denoising, background removal and de-ringing.
3. The method of claim 2 further comprising wavelet filtering with adaptive approximation and details levels in said signals.
4. The method of claim 3 further comprising real-time point-to-point implementation of wavelet-based filtering with high throughput FPGA algorithms.
5. The method of claim 3 further comprising background removal from said signals with adaptive selection of wavelet denoising levels and trend levels.
6. The method of claim 1 further comprising adaptively optimizing set-point deflection of the AFM's probe to perform imaging with minimal sample-dependent and environment-dependent repulsive force for determining sample surface topography.
7. The method of claim 6 further comprising filtering and adaptively optimizing set-point deflection of said probe to perform imaging with minimal sample-dependent and environment-dependent repulsive force for determining sample surface topography.
8. A method of measuring electric and electromechanical characteristics of a sample in non-resonant oscillatory mode of operation of a probe-based instrument, by applying electric modulation/a periodically varying voltage to a probe-sample location at a frequency higher than the sample or probe oscillatory motion and detecting the probe electric or mechanical response through variations of its oscillatory parameters at or near the modulation frequency and at its harmonics in the probe/sample touching and non-touching parts of an oscillatory cycle.
9. The method of claim 8 further comprising measuring sample piezo-response, which stimulates the sample expansion/contraction, detected by the probe amplitude and phase changes at the modulation frequency in the touching part of the cycle, and detecting electrostatic force and force gradient variations in the non-touching part of the cycle by monitoring changes in probe oscillatory characteristics at or near modulation frequency and its harmonics, using electric force microscopy or Kelvin force microscopy measurements.
10. The method of claim 8 , wherein measurements of magnetic force and gradients between a probe with ferromagnetic coating and a sample in the non-touching parts of the cycle enable magnetic force microscopy measurements in non-resonant oscillatory mode.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
April 7, 2014
August 18, 2015
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